Diabetic patients are generally recommended to perform a daily self-management of diabetes by measuring blood sugar levels by themselves. Blood sugar levels can be measured using blood component measuring devices. According to one blood component measuring device, it holds a test paper impregnated with a reagent which produces a color change dependent on the amount of glucose contained in a blood sample that is brought into contact with the test paper. In operation, a blood sample is applied to the test paper, and the degree of a color change produced by the reagent is optically measured to determine the blood sugar level of the blood sample. The determined blood sugar level is then displayed. Another blood component measuring device employs an electrochemical sensor for measuring the blood sugar level of a blood sample.
In order for a diabetic patient to sample its own blood, the diabetic patient uses a puncture instrument equipped with a puncture needle tip having an axially movable needle. The puncture needle tip, which is removably mounted on the puncture instrument, exerts repulsive force from an elastic body to a needle therein to cause the needle to project instantaneously and puncture the skin, e.g., a finger, a palm, an arm, or the like, of the patient for thereby letting a small amount of blood to flow out. After the puncture, the needle is retracted by a return mechanism.
Generally, the puncture instrument is used with the puncture needle tip mounted thereon, and the puncture needle tip is thrown away after use. Though hospitals and clinics have a considerably large number of puncture needle tips ready for use depending on the number of patients and the frequency of blood sugar measurements, they have a relatively small number of puncture instruments available. Therefore, if many patients need to be simultaneously measured for blood sugar levels, it may take a longer time to measure blood sugar levels for all the patients than usual because not enough puncture instruments may be available. Since a puncture needle tip has to be mounted on and removed from the puncture instrument for each measurement session, there are demands for simpler puncture instruments.
Japanese Patent No. 3795511 discloses a simple lancet assembly integrally combined with a puncture needle tip. The disclosed lancet assembly makes it unnecessary to mount and remove the puncture needle tip each time a blood sample is to be obtained.